I want a Grass Dragon because it's weaknesses and resistances alone would be out of this world!
Four regular weaknesses; Poison, Dragon, Flying, Bug
One super weakness(4x damage); Ice
One regular resistance; Ground
Three super resistances(.25x damage); Grass, Water, Electric
And neutral to eight types, meaning it doesn't get severely crippled by Dark, Steel or Psychic attacks, and Flamethrower ideally wouldn't OHKO or even 2HKO it.
And just think. it could learn Solar Beam and get Draco Meteor tutoring.